The present disclosure relates to dual coating systems that continuously coat both surfaces of a long substrate with a coating solution while feeding the long substrate.
International Patent Publication No. WO2011/001648 describes a dual coating system coating both surfaces of a substrate that will be the core of an electrode material of, for example, a secondary battery or a fuel cell with a coating solution containing active material. The dual coating system includes a die head for front face coating, a die head for back face coating, and a drying oven located downstream of both the die heads in a direction of feed of the substrate. In the dual coating system, both surfaces of the substrate are coated with the coating solution, and the coating solution is then dried to form an active material layer on each surface of the substrate.
The dual coating system includes rotator units and a rotator rotating section. The rotator units each include a pair of rotators between which the substrate is grasped from the front and back surfaces of the substrate, and are each independently provided on a corresponding one of both end portions of the substrate in the widthwise direction of the substrate, and the rotator rotating section individually modifies the orientations of the pairs of rotators of the rotator units with respect to the direction of feed of the substrate. This configuration allows the entire surface of the substrate being fed to be properly kept under outward tension, and allows the substrate to be stably fed without flapping and wrinkling the substrate.
Furthermore, the dual coating system includes end portion location determiners that are laser displacement sensors or sensors. The end portion location determiners can each determine the location of a corresponding one of end portions of the substrate in the widthwise direction of the substrate, and are each provided in the vicinity of a corresponding one of the rotator units and upstream or downstream thereof. International Patent Publication No. WO2011/001648 shows that when a signal from the end portion location determiner is monitored, and the location of the corresponding end portion of the substrate is outside a predetermined range, automatic control is performed to adjust, for example, the orientation of the rotator unit or the rotational speed of a drive roller forming one of the pair of rotators, and automatic correction control can be, therefore, performed such that the amount of the substrate displaced along the width of the substrate falls within the range of set values.